Sunan Ibn Majah 660
سنن ابن ماجه#660Sahihحَدَّثَنَا أَبُو مَرْوَانَ، حَدَّثَنَا إِبْرَاهِيمُ بْنُ سَعْدٍ، عَنِ الزُّهْرِيِّ، عَنْ مَحْمُودِ بْنِ الرَّبِيعِ، وَكَانَ، قَدْ عَقَلَ مَجَّةً مَجَّهَا رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ فِي دَلْوٍ مِنْ بِئْرٍ لَهُمْ .
It was narrated from Zuhri that:Mahmud bin Rabi' remembered that the Prophet spat into a bucket from a well that belonged to them
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih
In-book reference: 1:394